Capillary electrophoresis is widely applied in analytical and preparative separation processes in chemistry, biochemistry, and biotechnology. Conventional capillaries made of fused silica suffer from a number of drawbacks as they lack chemical stability. When subjected to high pH values, lack physical stability under mechanical stress, and during operation they show poorly reproducible electroosmotic flow (EOF) values after an exchange of the buffer solution. Developments to overcome these drawbacks have provided capillaries made of synthetic polymer materials such as polyethylene (PE), polypropylene (PP), poly(vinyl chloride) (PVC), polyfluorocarbon (PFC), and the like, for example. Studies of the electrokinetic properties of PE, PVC and PFC capillaries in aqueous solutions in dependence on pH are reported by Schutzner, W. and Kenndler, E. in: Anal. Chem. 64 (1992), p. 1991-1995. In the J. Microcolumn Separations, Vol. 5, No. 3, 1993, pages 246 and 247 it is described to coat the inner surface of hollow fibres of poly(butylene terephthalate) or polypropylene with polymers of acrylamide by graft polymerization
The capillaries made of silica or synthetic polymer materials both present another problem in the phenomenon of electroendosmosis or electroosmotic flow which arises from an electrokinetic potential between the solid capillary wall and the liquid medium. A further problem with polymer capillaries is the adsorption of substrates to be separated by the capillary wall. These phenomena interfere with the mobility characteristics of the components involved and may deteriorate component separation efficiency and decrease resolution.